Best practice for controlling potato volunteers and reducing sprouting in store with Fazor®

UK - August 16, 2012

Volunteer potatoes left behind from last year’s crops are one of the major sources of blight and, especially after this years very high blight pressure, growers are being advised to plan ahead to prevent the problem re-occurring in future years. Controlling volunteers can only be achieved by using an integrated control programme, which includes the application of the only in-potato crop solution, Fazor (maleic hydrazide).

Alex Nichols of Dow AgroSciences says that new research work has confirmed the effectiveness of Fazor in delivering excellent suppression of volunteers as well as reducing sprouting in store, with no detrimental effects on the crop or on processing quality.

“A foliar application of Fazor in second earlies and maincrop potatoes reduces the viability of small daughter tubers and so suppresses volunteers developing in the field after harvest. New trials data shows that Fazor gives excellent reduction of between 97% and 100% of volunteers in following crops. It also inhibits sprouting in store, with new trials demonstrating that Fazor significantly reduced sprouting by between 83% and 95% in a range of contemporary varieties tested 12 months following treatment.” says Alex.

“The timing for Fazor is just about here in many areas. There are a number of criteria that need to be met in order to optimise its performance. In terms of timing, you need to calculate back at least three but no more than five weeks from the intended burn down date. This allows sufficient time for the chemical to be taken up by the leaves and translocated to the tubers where it acts. The optimum timing is five weeks before harvest,” he advises.

In addition, each field needs to be checked for maturity and tuber size, using test digs. The smallest tubers required to reach marketable size should be greater than 25 mm across. If too many tubers are going through, it is worth waiting and re-sampling in a few days time,” Alex advises.

Fazor should be applied when the crop is actively growing and the haulm is mostly green, but with a few of the lower leaves turning yellow and most of the flowers having fallen off. The crop should not be stressed by drought, pests, diseases or high temperatures (in excess of 26ºC). This year water logging may be an issue to look out for in some instances.

“Potato volunteers arise when small sized tubers fall through the harvester webs or become detached from the plant at harvest. This year we may see a higher risk of undersized tubers. You can get up to 300,000 volunteers per hectare and they can remain viable for up to eight years. Potato volunteers must be controlled as they are a key source of blight and an important reservoir for other diseases, viruses and pests including Potato Cyst Nematodes. A planned and integrated approach to their control across the rotation is necessary, using wider potato rotations, min-tillage after harvest to allow frost to get to the chats, applying other herbicides such as the new double strength Dow Shield 400 in sugar beet, Starane and other fluroxypyr containing formulations in cereals and glyphosate in non-crop situations, but Fazor is still the only solution that can be applied in potatoes,” says Alex Nichols.

Growers and advisors can use the e-learning module for Fazor in order to get best results. The e-learning module can be found on-line at www.fazor.co.uk. Fazor is included in the Assured Produce Protocol. It is recommended that growers check with their supplier before making an application.

Fazor contains 600g/kg maleic hydrazide, formulated as a water-soluble granule and packed in a 5 kg bag. It is recommended on second earlies and maincrop potatoes (not on seed or first earlies) at a dose rate of 5 kg/ha in 350-500 litres of water. It should be applied to actively growing foliage, typically around 3 to 5 weeks before burn down and at least 12 weeks after crop emergence. It has a maximum number of treatments of one per crop and a latest time of application of 3 weeks before harvest. Fazor is fully approved for use on bulb onions and has specific Extension of Authorisation for Minor Uses (EAMU’s or SOLAs) for use in garlic, shallots, carrots and parsnips.